Ethynylcyclohexyl compounds as corrosion inhibitors



United tates Paten Patented July 25, 1961 This invention relates to corrosion inhibitors for use in aqueous hydrochloric acid to inhibit the corrosion of iron, steel, ferrous alloys or nickel exposed to said acid.

The new corrosion inhibitors are compounds having the formula CECH wherein R is a member of the group consisting of -H and lower alkyl radicals and X is a member of the group consisting of OH, SH, NH Cl, OCOOH OCOOC H OOH CH OH, OCH CHOHCI-I and PO 3. Thus, the compounds included are l-ethynylcyclohexyl alcohol, mercaptan, amine, chloride, acetate, ethyl carbonate, Z-hydroxyethyl ether, Z-hydroxypropyl ether and phosphite and the ring-substituted lower alkyl homologs thereof wherein the alkyl group contains up to about 6 carbon atoms. This class includes several new compounds, the preparation of which is described in the copending applications of Roger F. Monroe et 21., Serial No. 601,647, now Patent No. 2,802,878; Serial No. 601,650, now abandoned, Serial No. 610,655, now Patent No. 2,805,257 and Serial No. 601,656, now abandoned, all filed concurrently herewith.

According to the invention, the inhibitors are simply dissolved in the aqueous hydrochloric acid the corrosive action of which is to be inhibited. By aqueous hydrochloric acid we mean HCl in the presence of a significant amount of water and do not mean to exclude other substances. Only a small amount of the inhibitor is required. As little as a few thousandths of 1 percent, based on the acid solution, significantly reduces the corrosion of iron, steel and nickel exposed to the acid. The degree of inhibition increases with the concentration of the inhibitor up to a level of about 1 percent while beyond this point there is little advantage in using more inhibitor. For most applications, we prefer to use the inhibitor at a level of about 0.1 to 0.4 percent, this being adequate for most purposes.

The inhibitors of the invention are eliective not only at ordinary temperatures but also at elevated temperatures up to the decomposition point of the inhibitor. This point varies somewhat, depending on the particular compound being used, but all the inhibitors are effective up to at least 150 F. and many are eifective to 175, dependent somewhat on the concentration of the acid in which they are used. They are efiective in all concentrations of hydrochloric acid up to at least 37 percent, corresponding to commercial concentrated acid.

Applications in which our inhibitors are particularly effective include metal-cleaning and polishing baths, oil well-acidizing solutions, boiler-cleaning compositions an the like. i

In order to demonstrate the effectiveness of our inhibitors, a series of standardized tests was run wherein 0.4 percent of the inhibitor was added to a 10 percent solution of I-lCl in water held at 150 F and a coupon of AISI-1020 mild steel, previously pickled, cleaned, dried, and tared, was suspended in the acid solution.

After 16 hours at the coupon was removed, washed, dried and reweighed to determine the amount of metal removed during the test. This was then calculated as lbs. of metal removed per sq. ft. per day. Results of these tests are shown in Table I.

Table I Corrosion rate of 10 percent HCl at 150 F. on mild steel in the presence of 0.4 percent of an inhibitor havmg the formula CECE Corrosion Example R X Rate,

No. lb./sq. it./

day

1 H O 0.0052 H ocmononon. .0056 H P .0058 H .0059 0064 0069 .0089 .011 012 016 .015 .034 x-Methyl 197 H .237 (no inhibitor). 1.

Homologs of the compounds in the above table wherein R is an alkyl group containing up to at least 6 carbon atoms are also effective inhibitors.

Results generally paralleling those shown in Table I were obtained when similar tests were made, using other concentrations of HCl or lower temperatures, though the use of more dilute acid or lower temperature naturally resulted in a lower corrosion rate. Likewise, the use of other metals including iron, other types of steel, including stainless, or nickel gave generally similar results, the inhibitors being effective in each case even thought the observed corrosion rates varies according to the particular type of metal used.

The compounds of Examples 1, 5, 6, 8 and 12 may be made by the procedure described in British Patent 737,- 080. Those of Examples Zand 9 may be made by the reaction of the appropriate alkylene oxide with the corresponding alcohol. Those of Examples 3, 7 and 11 may be made by treating the corresponding alcohol or metal alcoholate with the appropriate acid chloride. Those of Examples 10 and 13 may be made from the corresponding alcohol by treatment with concentrated hydrochloric acid. Similarly, the compounds of Examples 4 and 14 may be made from the corresponding chlorides by reaction with concentrated NH OH or alkali metal hydrosulfide, respectively.

We claim:

1. An aqueous solution of hydrochloric acid containing, as a corrosion inhibitor therefor, about 0.1 to 1% of a compound having the formula CECH wherein R is a member of the group consisting of H and lower alkyl radicals and X is a member of the group consisting of OH, SH, --NH Cl, OCOCH OCOOC H OCH CH OH, OCH CHOHCH and PO 3.

2. A solution as in claim 1 wherein X is OH.

3. A solution as in claim 1 wherein X is --NH 4. A solution as in claim 1 wherein X is OC OC H' 5. A solution as in claim 1 wherein X is --PO 3.

6. A solution as in claim 1 wherein X is OCH CHOHCH References Cited in the file of this patent UNITED STATES PATENTS 1,169,341 Chrzesciuski et a1 Jan. 25, 1916 1,841,768 Straus et a1. Jan. 19, 1932 1,963,934 Carothers et a1 June 19, 1934 4 Ducamp et a1 Mar. 28, 1939 Humphreys et a1. June 18, 1940 Bruson et a1. July 29, 1941 Walker Aug. 8, 1944 Petering et a1. Mar. 20, 1945 Gardenier Sept. 3, 1946 Berger et a1 July 15, 1952 Humphlett Dec. 6, 1955 Skeeters et a1 Dec. 25, 1956 Schaaf et a1 Dec. 25, 1956 Lowes et a1. Sept. 3, 1957 Monroe et a1. Sept. 10, 1957 B'eiswanger et al Nov. 26, 1957 Bachtel June 10, 1958 Foster et al Mar. 31, 1959 FOREIGN PATENTS Great Britain Aug. 9, 1949 Germany Sept. 21, 1953 France Apr. 14, 1954 France May 26, 1954 Belgium Sept. 15, 1951 OTHER REFERENCES Corrosion Handbook by Uhlig, pages 910-912, publ. by John Wiley, N.Y., 1948. 

1. AN AQUEOUS SOLUTION OF HYDROCHLORIC ACID CONTAINING, AS A CORROSION INHIBITOR THEREFOR, ABOUT 0.1 TO 1% OF A COMPOUND HAVING THE FORMULA 